In recent years, considerable advances have been made in using photovoltaic cells or the like to directly convert solar energy into useful electrical energy. Typically, a plurality of photovoltaic cells are encased between a transparent cover sheet (e.g. glass, plastic, etc.) and a backsheet, to form flat, rectangular-shaped modules (sometimes also called “laminates”) of a manageable size (e.g. 2½′×5′). These modules are then shipped to a site where they are assembled into an array onto the roof of a building or the like where the array will be exposed to the sun.
While some modules are “unframed”, recently the trend has been towards providing frames around the peripheries of the modules to thereby increase the stability of the modules and to provide a positive means for installing the modules onto roofs or the like. Also for both structural and esthetic considerations, it is usually preferable to construct the frames of adjacent modules so that they overlap to conceal the necessary electrical wiring and provide a pleasing appearance on a roof. For a good, detailed description of the construction and operation of such solar modules, see U.S. Pat. Nos. 6,111,189 and 6,465,724 B1.
Typically, framed modules are bolted or clamped onto separate support structures, e.g. “stand-offs”, which, in turn, are securely bolted or screwed directly into the roof. The spots on the roof to which these support structures can be securely attached for a long life are effectively limited to those which are adequately supported by a framing member (e.g. a rafter) or roofing material strong enough to properly receive and retain the lag screws over the operational life of the array. This can create problems where the roof is shingled over slats or where the decking material is comprised of thin plywood, chipboard, or the like.
While framed modules have experienced commercial success, the installation of these modules can be relatively tedious and time consuming. That is, the task of (a) aligning two, relatively bulky and weighty modules, aligning the respective openings in adjacent frames, and (b) holding them in position while threading a lag screw or the like through the aligned openings and into the roof can present a difficult, and sometime frustrating task for a single installer.
Also, there is nothing to insure that once the openings in the adjacent frames are aligned that the frames will not shift slightly so that when, for example, a lag screw is threaded through the openings and into the roof, the screw will penetrate the roof at the precise point necessary to keep the modules parallel to each other. Any slight shift of the frames can result in a less that desirable appearance since some of the modules will be skewed in relation to the others.
Since esthetics are important, especially when the array of modules is highly visible, if skewing occurs, certain lag screws may have to be repositioned to properly align the modules to give the desired appearance. This can leaves holes in the roof which have to be sealed to prevent leaks. Further, the roofing material around the lag screws, themselves, should be sealed to prevent possible leaks. This may be difficult to do after the modules have been mounted since the accessibility to the screws is limited.
Since the total cost of any solar array includes its installation costs, any savings in time and man power needed in mounting the array become vital considerations in the overall economics of such an array. In view of the above, it can readily be seen that any savings in these costs can significantly make the use of solar arrays more competitive in the market place.